#include "WProgram.h"
void fill_buffer();
char spi_transfer(volatile char data);
void my_write(char mydata, int address);
byte read_eeprom(int EEPROM_address);
#define DATAOUT 11//MOSI
#define DATAIN  12//MISO 
#define SPICLOCK  13//sck
#define SLAVESELECT 10//ss

//opcodes
#define WREN  6
#define WRDI  4
#define RDSR  5
#define WRSR  1
#define READ  3
#define WRITE 2

byte eeprom_output_data;
byte eeprom_input_data=0;
byte clr;
int address=0;
//data buffer
char buffer [128];

void fill_buffer()
{
  int a =0;
  for (int I=50;I<178;I++)
  {
    buffer[a]=I;
    a++;
  }
}

char spi_transfer(volatile char data)
{
  SPDR = data;                    // Start the transmission
  while (!(SPSR & (1<<SPIF)))     // Wait the end of the transmission
  {
  };
  return SPDR;                    // return the received byte
}

void setup()
{
  Serial.begin(19200);

  pinMode(DATAOUT, OUTPUT);
  pinMode(DATAIN, INPUT);
  pinMode(SPICLOCK,OUTPUT);
  pinMode(SLAVESELECT,OUTPUT);
  digitalWrite(SLAVESELECT,HIGH); //disable device
  // SPCR = 01010000
  //interrupt disabled,spi enabled,msb 1st,master,clk low when idle,
  //sample on leading edge of clk,system clock/4 rate (fastest)
  SPCR = (1<<SPE)|(1<<MSTR)|(1<<SPR1)|(1<<SPR0);
  clr=SPSR;
  clr=SPDR;
  delay(10);
  //fill buffer with data
  fill_buffer();
  //fill eeprom w/ buffer
  digitalWrite(SLAVESELECT,LOW);
  spi_transfer(WREN); //write enable
  digitalWrite(SLAVESELECT,HIGH);
  delay(10);
  digitalWrite(SLAVESELECT,LOW);
  spi_transfer(WRITE); //write instruction
  address=0;
  spi_transfer((char)(address>>8));   //send MSByte address first
  spi_transfer((char)(address));      //send LSByte address
  //write 128 bytes
  digitalWrite(SLAVESELECT,HIGH); //release chip
  
  for (int I=0;I<128;I++)
  {
    my_write( buffer[I], I);
  }

  delay(3000);
  Serial.print('h',BYTE);
  Serial.print('o',BYTE);
  Serial.print('\n',BYTE);//debug
  delay(1000);
}

void my_write(char mydata, int address) {
  Serial.print(mydata,DEC);
  Serial.print(" - write ");
  Serial.print(address,DEC);
  Serial.println();
  digitalWrite(SLAVESELECT,LOW);
  spi_transfer(WREN); //write enable
  digitalWrite(SLAVESELECT,HIGH);
  delay(10);
  digitalWrite(SLAVESELECT,LOW);
  spi_transfer(WRITE); //write instruction
  spi_transfer((char)(address>>8));   //send MSByte address first
  spi_transfer((char)(address));      //send LSByte address
  //write 128 bytes
  spi_transfer(mydata); //write data byte
  digitalWrite(SLAVESELECT,HIGH); //release chip
}

byte read_eeprom(int EEPROM_address)
{
  //READ EEPROM
  int data;
  digitalWrite(SLAVESELECT,LOW);
  spi_transfer(READ); //transmit read opcode
  spi_transfer((char)(EEPROM_address>>8));   //send MSByte address first
  spi_transfer((char)(EEPROM_address));      //send LSByte address
  data = spi_transfer(0xFF); //get data byte
  digitalWrite(SLAVESELECT,HIGH); //release chip, signal end transfer
  return data;
}

void loop()
{
  eeprom_output_data = read_eeprom(address);
  Serial.print(eeprom_output_data,DEC);
  Serial.print(" - read ");
  Serial.print(address,DEC);
  Serial.println();
  address++;
  if (address > 1026) {
    address = 0;
    Serial.print(" reset to 0\n");
  }
  delay(20); //pause for readability
}
int main(void)
{
	init();

	setup();
    
	for (;;)
		loop();
        
	return 0;
}

